Electric motor systems typically include motor control circuits, such as inverters. Power is supplied to the motor control circuits by a direct current (DC) bus having a DC bus capacitor coupled between the high and low voltage nodes of the DC bus. When the DC bus is powered down, the energy stored in the DC bus capacitor is typically discharged by connecting the DC bus to a dedicated discharge circuit which typically includes a large resistor or other dissipative device employed for discharging the DC bus capacitor. Conventional dedicated discharge circuits, which are actively connected to the DC bus only when the discharge function is desired, to reduce system power losses (i.e., those system power losses which would result from continuous connection of the dissipative device to the DC bus), add both size and cost to the motor control circuitry.
Accordingly, it is desirable to provide a DC bus discharge scheme which employs existing circuitry to perform the necessary discharge functions. In addition, it is desirable to provide a reliable DC bus discharge scheme which does not require extraneous information. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.